The present invention relates generally to reducing the amount of power consumed by an integrated circuit and more particularly to reducing the power consumed by a dynamic random access memory (DRAM) during a fault condition.
Typical memory devices are comprised of a plurality of memory cells, each storing one bit of data. The memory cells may be arranged in arrays; each memory cell, for example, connected to a wordline and a digitline. The memory device may also include peripheral devices, such as drivers, sense amps, input/output devices, and power supplies, etc., that are used to locate memory cells, access the memory cells, and store information within and read information from the memory cells, among others.
The amount of data that is stored by a memory device is limited by the number of memory cells that comprise the memory device. The number of memory cells within a given area of a memory device may be referred to as the cell density. An increase in cell density typically results in an increase in the amount of data that can be stored by a device. Thus, circuit designers continually try to increase the cell density, for example, by decreasing the size of each memory cell and/or freeing some of the space occupied by the peripheral circuits so that additional memory cells can be provided on the memory device. Increasing cell density, however, has created several problems. For example, current leakage though the cell access devices (e.g., sense amps, column select devices, input/output devices, etc.) has increased with decreasing cell access transistor geometries.
One method of reducing current leakage through the cell access devices includes driving the wordlines to a negative voltage. Negative wordline voltage (NEGWL) refers to a wordline voltage that is less than GROUND potential, for example, between −0.1 and −1 volts. A typical NEGWL for the current state of the art devices may be between −0.3 and −0.5 volts. Reducing current leakage using NEGWL, however, creates additional problems should a wordline-to-digitline short occur. More specifically, driving the wordline to a negative wordline voltage may increase the amount of current that flows through a fault (e.g., a short circuit) and/or may increase the current that flows though other peripheral circuits (e.g., the sensing devices), for example, while in a standby mode.
Thus, there exists a need for an apparatus and method for reducing current flow in a memory device during a fault (such as a wordline-to-digitline short), for reducing the current leakage through peripheral circuits, and that overcomes the other limitations inherent in prior art.